Fuel Injector: Description and Operation

Fuel Injector:

Purpose
The fuel injector both meters and atomizes fuel delivered to the engine.

Description
The fuel injector is:

^ an electro-mechanical device.

^ mounted in the cylinder head pockets.

^ positioned so that their tips are directing fuel just before the engine intake valve.

Construction
The fuel injector valve body consists of:

^ solenoid

^ needle and valve assembly

^ director/metering plate

Operation
An electrical control signal from the powertrain control module (PCM) activates the fuel injector solenoid, causing the needle to move inward, off the seat, allowing the fuel to flow. Since the fuel injector flow orifice is fixed and the fuel pressure drop across the injector tip is constant:

^ fuel flow to the engine is regulated by the length of time the solenoid is energized.

^ atomization of the fuel is obtained where the fuel separates.